Blovers are not required because there are only a few airborne zombies.
Do as you normally do in the first stage. Planting two columns of Twin Sunflowers (not under power Tiles) will help you plant many offensive plants to get ready for the Gargantuar Primes' appearance.
Try to plant at least one Winter Melon in each lane. Then, plant one column of Citrons and Laser Beans. When the first huge wave comes, a Gargantuar Prime enters your lawn. Immediately, use an E.M.Peach to stun it before its laser burns your Winter Melons. Then, use Plant Food on a Citron in the same lane where the Gargantuar Prime appears to kill it instantly. Make sure there are no Disco-tron 3000s in front of the Gargantuar Prime or the Citron will kill the Disco-tron 3000, instead.
When the final wave arrives, another two Gargantuar Primes arrive. Use an E.M.Peach again to stun them and try to plant as many offensive plants in front of them as possible. This will help kill them faster before it attacks and throw a Bug Bot Imp to destroy your defense.